ABSTRACT Title: Outcomes of Omission of Radiation With Lumpectomy (BCS) Among Low-Income Women Background: There is little information describing the patterns of health care and outcomes in financially needy women with breast cancer in the United States. In previous work we have developed and validated an integrated database linking North Carolina (NC) fee-for-service Medicaid claims and tumor registry data for all cases in 1998 and 1999 (N=1,402) and documented the high validity of this data integration strategy to study adjuvant treatment (radiation and chemotherapy) in Medicaid. We find that approximately 45% of women who received BCS did not receive radiation within 12 months from date of diagnosis. Data obtained from the Social Security Death Master File showed that women with BCS and no radiation have 1.8 times the risk of dying during the subsequent median 72 month period than those who were radiated, adjusting for comorbidity, stage, and deaths in first year of surgery. Objectives: Proposed is a 2-year project to ascertain the extent that omission of radiation is linked to poorer survival in women with fee-for-service Medicaid diagnosed with breast cancer in years 1997-2001 in North Carolina. Specifically, we propose to identify and analyze: 1) 7-year recurrence with BCS using claims and registry data with a validated algorithms; 2) case-fatality (all cancer deaths, and breast cancer deaths vs all other causes) using the National Death Index Plus system; and 3) to add hormonal therapy to the dataset using existing Medicaid prescription claims to describe access and as a predictor in the recurrence and survival models. We will use regression and survival analytic models to compare rates of BCS (+/- radiation) on recurrence and survival, adjusting for age, comorbidity, tumor size, stage, tamoxifen prescription status, hormone receptor status. Future Directions: We plan to develop community and health systems interventions to promote access to radiotherapy among low income women, and investigate the role of health care resources and Infrastructure on cancer care disparities in this population.